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Cooling Power Test

A cooling power test is a measure of the cooling power at 100mK. This is accomplished by finding the maximum power placed on the mixing chamber while maintaining the mixing chamber temperature at 100mK. The two parameters to adjust are the powers applied to the mixing chamber and to the still. The spec on the fridge is 400$ \mu$ W, though upon delivery we only achieved 350$ \mu$ W.

Note: For the most accurate measurement, the test should be done with nothing attached to the mixing chamber plate.

  1. Once the system is at base temperature, begin stepping the mixing chamber heater up until the mixing chamber temperature stabilizes at 100mK. It may take several minutes to stabilize, and the system may over shoot before settling.

  2. Once the system has stabilized, adjust the power on the still heater to lower the temperature on the mixing chamber. You will need to determine if the still power needs to go up or down. Continue adjusting the power until the mixing chamber temperature is at a minimum.

  3. Repeat the above two steps, until you reach a setting where adjusting the still power either up or down only raises the mixing chamber temperature.

Notes:


next up previous contents
Next: Base Temperature Test Up: Tests Previous: Tests   Contents
Jonathan Ouellet 2014-08-26